Arming device for aerial bombs



y 1965 c. B. CRUMB, JR I 3, ,8

ARMING DEVICE FOR AERIAL BOMBS Filed March 19, 1945 2 Sheets-Sheet 1 IN V EN TOR.

C35 1 Crumb wm y 6, 1965 c. B. CRUMB, JR 3,192,858

ARMING DEVICE FOR AERIAL BOMBS Filed March 19, 1945 2 Sheets-Sheet 2" IN V EN TOR.

Carl Cfumb United States Patent 3,192,858 ARMING DEVIEE FOR AERIAL BflMiiS Carl R. Crumb, .lr., Cincinnati, Ohio, assignor to the United States of America as represented by the United States Atomic Energy Commission Filed Mar. '19, 1945, Ser. No. 583,497 3 Claims. (Cl. 102-812) This invention relates to bombs or other ordnance such as may be dropped from airplanes and the like. More particularly, it is directed to a novel means whereby the detonation of such bombs or similar ordnance can be controlled.

Heretofore various types of mechanisms have been designed for the arming or detonating of aerial bombs or flares in which the rotation of a fan or propeller blades at the forward end of the bomb are utilized to withdraw pins that lock the detonating mechanism. Other devices, similarly activated, provide means for detonating a bomb after a predetermined lapse of time.

Primarily such wind operated arming devices are useful in permitting an aerial bomb to clear the carrying plane before becoming armed and operative, or to permit a flare to fall clear of the carrying plane before being ignited. The number of rotations the propeller makes is usually about forty or fifty thus presenting a comparatively short delay before operation. Efforts to increase the number of rotations, and thereby increase the period of time between entrance of the bomb into the surrounding atmosphere and the occurrence of the arming, detonating or igniting step, raises mechanical difliculties which are solved by the application of principles of the present invention.

Another problem is presented in various types of arming and. detonating devices now commonly used in connection with aerial bombs and the like, in which compression of one or more springs is a prerequisite for the desired activation of the device. Such compression may be necessary to release locking pins or the like as noted above or may be required in the operation of an electric switch. Means for avoiding such spring compression become complicated and expensive to manufacture and add, by the utilization of many moving parts, to the probability that the mechanism may not properly operate with the result that the bomb or flare may not be armed and/ or detonated at the predetermined time.

Furthermore, in such devices where the compression of a spring is required, an air pressure activated means such as a propeller must be large enough to provide suflicient torque for the ultimate compression or tension of the spring. Since the torque increases in proportion to the spring constant the accurate timing of the mechanism becomes a diflicult and haphazardous undertaking.

It follows that one object of this invention is to provide a simple positive means for arming and/ or detonating an aerial bomb.

Another object is to provide means for rapid adjustment in the arming and/ or detonating mechanism whereby the position of the bomb with respect to the carrying plane is made a factor in the arming or detonating of the bomb, flare or the like.

A further object is to provide an arming mechanism that is readily adaptable to various types of spring loaded arming anddetonating devices used in aerial bombs and the like which permits a longer delay in activation than previous types. 7 V v It is a still further object of this invention to provide an arming and/ or detonating device in which the activating means exert a progressively increasing force whereby spring forces which maintain the parts in fixed relationship until a predetermined time, may be overcome.

3,192,858 Patented July 6, 1965 In accordance with the objects above stated and in the practice of the present invention a preferred mechanism comprises an operative part that is controlled in its longi tudinal movement by a screw disposed to turn in a predetermined ratio to the rotation of a wind actuated propeller. This operative part which is called a slide, is pivotally attached to the center pin of a linkage system of toggle levers one of which engages a reciprocable member disposed to operate a spring switch or other type of arming or detonating device. The toggle lever system is one which afiords an increasing mechanical advantage substantially proportional to its displacement thereby overcoming an increasing counteracting force of the springs that control the operation of an electrical switch or a mechanical type of arming or detonating device and normally urge such a mechanism in an unarmed position.

It is also desirable in such a device to provide means for adjustment so that the number of revolutions the propeller makes before arming and/or detonation of the bomb takes place may be readily changed. In this way it is possible to control the point of arming or detonation at a predetermined distance from the carrying plane or the target as the case may be. This adjustment may be accomplished by changing the gear ratio of the driving portion of the mechanism. This'method offers .a coarse adjustment which would be governed by the particular type of bombingoperation contemplated. A fine adjustment is also provided in permitting end-way or longitudinal movement of the propeller shaft disengaging the driving gears thus permitting rapid setting of the relative position of the toggle linkage system before release of the bomb.

In order to understand the present invention better, reference is made to the accompanying drawings which are made part of this specification, wherein various embodiments of the principles of the invention are shown. In all of the figures the same reference characters are used to designate similar parts.

FIGURE 1 shows an elevation partly in section of an arming device constructed according to the principles of this invention which is used in activating an electrical circuit.

FIGURE 2 is another view of the device, largely in section, taken on the line 22 in FIGURE '1.

FIGURE 3 is a fragmentary representation of an aerial bomb, partly in section, showing the employment of the principles of this invention to arm an impact type fuse.

Referring now to the drawings and more particularly FIGURES 1 and 2, in which a preferred form of invention is illustrated, a wind operated propeller 1 is made integral with a rotatably mounted shaftZ by means of cooperating threads on the shaft and in the hub of the propeller. The shaft 2 is capable of limited longitudinal movement, the limitation being imposed by the spring 3 and the collar 4 which is fixed in its position on the shaft 2 by a set screw (not shown). The spring 3 is maintained under slight compression in its normal position by adjustment of the retaining nut 5. A twelve tooth pinion 6 is also fixed in its position on the shaft 2 by a set screw (not shown) and engages the sixty tooth gear 7 thus reducing the rotation of the shaft 2 in a five to one ratio.

The collar 4 is preferably made in the form of a round 3 vice during storage or transportation of the bomb in which the arming device is used.

In order to permit rapid adjustment of the position of the toggle levers 13 and 14 and thereby the relative position of the plunger 16 (thus permitting adjustment of the device to operate after a predetermined number of revolutions of the propeller) the shaft 2 may be moved longitudinally to permit the pinion 6 to be disengaged from the gear 7. However, as noted above adjustment of the spring 3 is such that the shaft 2 is normally urged to a position in which the gears 6 and 7 are in engagement.

The gear 7 is attached to a shaft 8 which has .a threaded portion 9 to engage internal threads on a rider nut pivotally mounted in the slide 10 by means of the pin 11. In order to further reduce the rotational motion of the propeller it is preferred to cut about forty-eight threads to the inch on the threaded portion 9 of the shaft 8 and the rider nut is similarly threaded. The slide also accommodates the pin 12 which forms the center pivot of the toggle levers 13 and 14. Lever 13 is made of two leaves, as is more clearly shown in FIGURE 2 in order to facilitate manufacture and is pin connected to the bracket 15 to permit rotation about that point. Lever 14 is connected by a clevis and pin arrangement to the sliding member 16 The sliding member 16 activates a switch, shown diagrammatically in the drawing, which has as essential features a contact lever 17 and a spring 18. The switch is incorporated into an electric circuit indicated by the wires 19 which is used for detonating the explosive in the bomb upon the occurrence of a predetermined event such as approach to within a certain distance of the target when using a proximity (i.e. radar) fuse. The entire device is preferably incorporated into a casing 20 which serves to support the various elements in fixed re lationship and which is fitted into the forward end of the bomb casing 21 by means of threads or the like.

In operation, the toggle levers 13 and 14 would be set in an unarmed position indicated by the dotted outline in FIGURE 1. Upon release from the carrying plane and the commencement of free flight of the bomb, the propeller 1 turns the shaft 2 at a predetermined velocity based upon the surface presented by the propeller to the surrounding atmosphere. In so turning and through the reduction gear arrangement 6 and 7, the shaft g with its threaded portion 9 is caused to rotate in the nut pivotally mounted in the slide 10. The propeller rotation is thus reduced and translated to translatory movement of the slide 10 toward the leading (i.e. downwardly) end of the bomb and as a result the toggle lever linkage 13 and 14- is drawn toward horizontal alignment. An increasing force (proportional to the cosine of the angle formed by the lever 13 or 14 and a horizontal line through the pin connection at 15 and the clevis pin connecting links 14 and 16) is transmitted through sliding member 16 serving to overcome the counter-acting increasing force of the spring 18. After a number of revolutions of the propeller 1 which can be predetermined by adjustment of the position of the toggle lever linkage before release, the contact arm 17 is moved to a position which closes the electrical circuit indicated by the wires 19. Since in an arrangement such as described about eighty revolutions of the propeller are necessary to give maximum movement of the sliding member 16 from unarmed to armed position, the bomb will have fallen a substantial distance from the carrying plane before arming takes place. If, then, due to some defect in other parts of the detonating system, the bomb explodes immediately upon being armed, no damage will be caused to the plane or injury to its personnel.

In another embodiment the pjrinciples of this invention are used in an arming device in conjunction with an impact type fuse. As idicated in FIGURE 3 the entire arming device is slidably mounted in the nose of the bomb. A striker pin is rigidly held in the bomb and maintained in alignment with the percussion cap 23 attached to the casing 20. The percussion cap which may be any standard type, is connected to a length of primacord 25 which leads to the main charge of the bomb (not shown). In this embodiment the device is normally urged to the unarmed position (indicated by the broken line representation) by the spring 13. In that position the pin 22 is prevented from communicating with the percussion cap 23 by the sliding member 16. A hole 24 drilled through the sliding member permits the cooperation of the striker pin and percussion cap when the armed position is attained.

The operation of this embodiment would be somewhat as follows: After setting in the unarmed position and release from the carrying plane the mechanism through the rotational motion of the propeller causes the sliding member 13 to move longitudinally thus bringing the striker pin 22 into communicating alignment with the percussion cap 23. Upon impact the striker hits the percussion cap and thereby initiates the detonation of the explosive contained in the body of the bomb.

While specific embodiments of the invention have been described it may be seen that changes and modifications may be made therein by one skilled in the art. However, it is intended that no limitation be placed on the scope of this invention by reason of the specific details and mode of operation hereinabove set forth. For example, the motion of the slide member may be changed so that the toggle action is reversed by changing the pitch of the propeller. The threads on the screw and nut may be made so that clockwise rotation of the screw will produce upward or downward movement of the nut. Similarly, the spring loaded switch or mechanical system may be varied in operation and manner of assembly.

It should be further noted that the invention as hereinabove described is used to overcome an increasing force though the propeller torque is constant. It is apparent that this application is not essential. The simplicity of the mechanism and the adaptability thereof to any type of aerial bomb or flare for arming purposes and/or detonating purposes, as a unit to be inserted in the bomb or flare, or incorporated as integral with them, renders the device of this invention generally useful.

It should, therefore be understood that the detailed description of the presently preferred embodiment is set out above to illustrate the benefits and objects of the invention with the reservation that such changes as are given above by way of example and others that affect the combination and/or construction of the various elements may be made without departing from the spirit and scope of the invention as defined in the subjoined claims.

What is claimed is:

1. An arming device for an aerial bomb, comprising a wind operated propeller fixed on a rotatably mounted shaft, a gear train to transmit the propeller torque on said shaft to a screw, said gear train being normally engaged and adapted to be disengaged by longitudinal movement of said shaft, a slider link co-operative with and adapted to move longitudinally with respect to said screw by the rotation of said screw, a toggle linkage having a movable pivot point thereof attached to said slider link, a plunger adapted to be given reciprocal motion by said toggle linkage and an electrical switch mechanism normally urged in an unarmed position activated by said plunger.

2. An arming and detonating device for an aerial bomb, comprising a wind operated propeller, a screw, means mechanically coupling the screw to the propeller so that the screw rotates in fixed ratio with the rotation of said propeller, a slider link having a threaded nut supported therein which engages said screw whereby the link is adapted to be moved longitudinally with respect to said screw by the rotation of said screw, a toggle linkage comprising two arms and having a movably pivot point thereof attached to said slider link; a plunger, stationary means pivotally supporting the free end of one arm of the toggle linkage and means pivotally interconnecting the free end of the other arm of the toggle linkage and the plunger, whereby the plunger is adapted to be given reciprocal motion by said toggle linkage, and a spring loaded switch having an activation member supported in the path of motion of said plunger.

3. An arming device for an aerial bomb, comprising a wind operated propeller fixed on a rotatably mounted shaft, a gear train, including a gear fixed on the propeller shaft, mechanically coupled between the propeller shaft and a screw, means providing axial motion of the propeller shaft to uncouple the gear train, a slider link comprising an elongated member, a nut element pivotally supported on one end of said slider link and engaging the screw whereby it is adapted for longitudinal translation by rotation of the screw, the toggle linkage comprising first and second arms each having a first and a second end, means for pivotally connecting the first ends of the first and second arms together and to the free end of the slider link, means for pivotally supporting the second end of the first toggle link arm to a fixed support,

a plunger comprising an elongated element supported for longitudinal translation in a direction normal substantially to the axis of said screw, means pivotally connecting the second end of the second toggle linkage arm and a first end of said plunger, and an electrical switch having a circuit closing element supported with the circuit closing element in the path of said second end of said plunger.

References Cited by the Examiner 20 SAMUEL FEINBERG, Primary Examiner ALEX BISHOFF, JAMES L. BREWRINK, Examiners. 

1. AN ARMING DEVICE FOR AN AERIAL BOMB, COMPRISING A WIND OPERATED PROPELLER FIXED ON A ROTATABLY MOUNTED SHAFT, A GEAR TRAIN TO TRANSMIT THE PROPELLER TORQUE ON SAID SHAFT TO A SCREW, SAID GEAR TRAIN BEING NORMALLY ENGAGED AND ADAPTED TO BE DISENGAGED BY LONGITUDINALLY MOVEMENT OF SAID SHAFT, A SLIDER LINK CO-OPERATIVE WITH AND ADAPTED TO MOVE LONGITUDINALLY WITH RESPECT TO SAID SCREW BY THE ROTATION OF SAID SCREW, A TOGGLE LINKAGE HAVING A MOVABLE PIVOT POINT THEREOF ATTACHED TO SAID SLIDER, A PLUNGER ADAPTED TO BE GIVEN RECIPROCAL MOTION BY SAID TOGGLE LINKAGE AND AN ELECTRICAL SWITCH MECHANISM NORMALLY URGED IN AN UNARMED POSITION ACTIVATED BY SAID PLUNGER. 